1. Field of the Invention
The present invention relates to: an image processing apparatus such as a multifunctional machine, a printer, a facsimile, or a MFP (Multi Function Peripheral) collectively having these functions; a communication method for the image processing apparatus; and a recording medium with a communication program stored on the image processing apparatus.
2. Description of the Related Art
The following description sets forth the inventor's knowledge of related art and problems therein and should not be construed as an admission of knowledge in the prior art.
In recent years, people use such an image processing apparatus as described above more often in the network environment by connecting it to communication devices such as network switches and hubs.
ErP Directive Lot 6, European Commission's eco-design directive aiming at reducing the environmental impact of energy-related products (ErPs), requires such MFPs as described above reduce stand-by power consumption to a predetermined value or below in a phased fashion.
Although ErP Directive Lot 26, which relates to network stand-by losses, does not mention power consumption just like Lot 6, it should be preferred to reduce power consumption at least to the same level as Lot 6 in order to achieve energy-saving, also while such MFPs are connected to the network.
Actually, while such MFPs are connected to the network without packet communication, the physical layer device (also to be referred to as PHY [abbreviation of “physical layer”]), which is the lowest layer in computer networking, consumes nearly the same amount of power as it does while they are connected to the network performing packet communication: 500 mW with the communication rate of 1 Gbps (bps: bits per second), 500 mW with the communication rate of 100 Mbps.
IEEE 802.3az to be publicly introduced soon is suggesting a new standard power-saving mode (LPI [Low Power Idle] mode) aiming to achieve low power consumption while keeping an idle connection without communication. By using this power-saving mode, the physical layer consumes only 100 mW or below while keeping an idle connection without communication.
However, it depends on available features of communication devices on the other end of the connection; if communication, devices on the other end of the connection, capable of communication of up to 1 Gbps, do not support the new standard mode, the physical layer would consume as much power as ever, almost 500 mV. This would lead to a sleep power consumption of more than 0.5 W, not achieving power savings. The communication rate of the image processing apparatuses may be adjusted to up to 100 Mbps in order to achieve power savings. Then, however, even if the communication devices on the other end of the communication, which are capable of up to 1 Gbps, support the new standard mode, there would be another problem: the image processing apparatuses could perform even data communication only at up to 100 Mbps.
Disclosed in Japanese Unexamined Patent Publication No. 2007-276341 is a printing apparatus which slows down the rate to communicate with other communication devices, before switching to power-saving mode. Specifically, a printing apparatus, which is provided with a controller instructing a LAN controller to control the communication rate, is configured to instruct the LAN controller to slow down the communication rate if judging the power supply mode should be canceled in order not to provide power to the controller. After that, a power supply cuts down power to the controller.
Disclosed in Japanese Unexamined Patent Publication No. 2006-293983 is a technology for a network communication device to adjust the communication rate immediately without any communication errors when switching to energy-saving mode such as power-saving mode. Specifically, when switching to energy-saving mode, a network communication device cuts down the signaling link to the other end of the connection by employing loopback mode; select a communication rate within the range of available communication rates from both ends of the connection, which is slower than that in regular mode; and auto-negotiate with the other end by cancelling loopback mode. Here, by auto-negotiation, the network communication device applies the communication rate slower than that in regular mode, which is selected by the network communication device itself, to the other end of the connection in order to perform communication therewith at the slower communication rate.
Disclosed in Japanese Unexamined Patent Publication No. 2004-048532 is a technology for a network interface device to achieve low power consumption of an entire network system by freely switching the power state of the network interface device itself, between regular state and power-saving state. In this network system: a primary apparatus, which is capable of being attached to by the network interface device, performs communication with another apparatus via a network; and the network interface device monitors by its own signal sensor a packet signal coming into the primary apparatus after being filtered by a switch or hub and controls by its own clock controller the clock frequency applied to its own CPU.
Conventionally, as described above, there are the following problems: even an image processing apparatus such as a MFP, having power-saving function, cannot achieve low power consumption if a communication device on the other end of the connection does not have power-saving function, too; and an image processing apparatus, which is configured to perform communication at a low rate, can perform even data communication only at up to that low rate, even if a communication device on the other end of the connection has power-saving function, too.
In addition, with the technologies from Japanese Unexamined Patent Publications No. 2007-276341 and No. 2006-293983, there is another problem: changing the communication rate before and after switching between power-saving mode and regular mode may cause packet loss due to a link-down. Also, with the technology from Japanese Unexamined Patent Publication No. 2004-048532, there is another problem: the CPU of a network interface apparatus needs to change the clock frequency before and after switching between power-saving mode and regular mode. Therefore, the technologies from Japanese Unexamined Patent Publications No. 2007-276341, No. 2006-293983, and No. 2004-048532 do not provide perfect solutions to the following problems: even an image processing apparatus such as a MFP, having power-saving function, cannot achieve low power consumption if a communication device on the other end of the connection does not have power-saving function, too; and an image processing apparatus, which is configured to perform communication at a low rate, can perform even data communication at that low rate even if a communication device on the other end of the connection has power-saving function, too.
The description herein of advantages and disadvantages of various features, embodiments, methods, and apparatus disclosed in other publications is in no way intended to limit the present invention. Indeed, certain features of the invention may be capable of overcoming certain disadvantages, while still retaining some or all of the features, embodiments, methods, and apparatus disclosed therein.